Device for delivering a biomaterial

ABSTRACT

A device for delivering small spheres of biomaterial into a determined portion of a bone including a cylindrical hollow body of inside diameter D 1  having a filling first end and a second end provided with a snap-fastener, a shutter-forming guide rod having a main portion that is cylindrical with an outside diameter D 2  and presenting an enlarged cylindrical portion suitable for co-operating with the snap-fastener of the body, and a piston constituted by a cylindrical part presenting an outside diameter D 3  and an axial bore of diameter D 4 . The diameter D 3  is slightly smaller than the inside diameter D 1  of the body and the inside diameter D 4  is slightly greater than the diameter D 2  of the rod in such a manner that, once the snap-fastener has been released, the rod can slide inside the piston, and the piston can slide inside the body.

This application is a filing under 35 USC 371 of PCT/FR02/03185, Sep.18, 2002.

The present invention relates to a device for delivering small spheresof biomaterial into a determined portion of a bone.

In order to put into place certain implants or orthopedic structuressuch as a screw-and-plate system in a particular location of a bone,e.g. in the head of the femur (femoral metaphysis), it is necessaryinitially to use an auger to make a cavity that will subsequently beoccupied by the implant or the orthopedic structure, i.e. the screw andthe barrel of the plate, in the particular example under consideration.In order to ensure that the implant or the orthopedic structure is heldin its cavity, it is necessary to insert a biomaterial into the cavityprior to introducing the screw or the implant, in order to stabilize theorthopedic structure.

At present, the cavity is filled with biomaterial manually using acuret. The curet is handled so as to fill in progressively the existingbone defect. A graft-pusher is used to push the biomaterial in variousdirections so as to distribute said material better within the cavity.The disposition of the material in the cavity is monitored by using animage intensifier.

Thereafter, the screw is slid on the pin that is subsequently going toadvance in the middle of the biomaterial, running the risk of eitherconflict with the biomaterial (rubbing, breaking up the material, metalparticles possibly becoming detached in the screw), or else entrainingsaid material into the head of the femur, which is undesirable. Inaddition, the length of time needed to fill in the cavity withbiomaterial using that technique is about 15 minutes.

It will thus be understood that that technique of delivering biomaterialinto the cavity by means of a curet and a graft-pusher presents numerousdrawbacks. In particular, it increases the duration of surgery, inparticular because of the verifications that need to be performed.Furthermore, it is difficult to ensure that the biomaterial is properlydistributed within the cavity.

There therefore exists a real need to have a device for deliveringbiomaterial into a predetermined portion of a bone that enables thefilling of the cavity with the biomaterial to be accelerated and thatenables the distribution of the biomaterial within the cavity to beimproved.

To achieve this object, the invention provides a device for deliveringsmall spheres of a biomaterial into a determined portion of a bone, thedevice being characterized in that it comprises:

-   -   a cylindrical hollow body of inside diameter D1 having a filling        first end and a second end provided with snap-fastening means;    -   a shutter-forming guide rod having a main portion that is        cylindrical with an outside diameter D2 and presenting, close to        its second end, an enlarged cylindrical portion suitable for        co-operating with the snap-fastening means of the body to secure        said rod in temporary manner in said body; and    -   a piston constituted by a cylindrical part presenting an outside        diameter D3 and an axial bore of diameter D4, the diameter D3        being slightly less than the inside diameter D1 of the body and        the inside diameter D4 being slightly greater than the diameter        D2 of the rod so that after the snap-fastening has been        released, said rod can slide inside said piston and in a manner        that is proof against the spheres, and the piston can slide in        the annular space that exists between said rod and said body and        in a manner that is proof against the spheres.

It will be understood that because of the possibility of moving the bodyof the device relative to the rod, and more precisely relative to itsshutter-forming enlarged cylindrical portion, it is possible to locateaccurately the zone in which the spheres are to be put into place in thecavity. It will also be understood that because of the action of thepiston whose outside diameter is smaller than the diameter of the bodyand thus of the cavity, it is possible to obtain a good distribution ofbiomaterial spheres against the wall of the cavity.

In a preferred embodiment, the rod includes an axial bore opening outinto its second end that is provided with an enlarged portion, the boreextending over at least a fraction of the length of the rod.

The axial bore of the rod enables the entire device to be guided whileit is being inserted into the cavity by means of a pin that haspreviously been put into place.

Also preferably, said filling first end of the hollow body is extendedby a piece having a frustoconically-shaped recess opening out into saidaxial bore of said body. This flared portion makes it easier to fill theannular space between the body and the rod with spheres, in the mannerof a funnel.

Also preferably, said snap-fastening means disposed at the second end ofsaid body comprise longitudinal slots formed in the second end of saidbody and portions in relief disposed at the second end of said body andprojecting into said axial bore, and said enlarged cylindrical portionof the rod includes a substantially cylindrical side face in which agroove is formed suitable for receiving the portions in relief on saidbody.

Other characteristics and advantages of the invention will appear betteron reading the following description of a preferred embodiment of theinvention given by way of non-limiting example. The description refersto the accompanying figures, in which:

FIG. 1 is an elevation view of the body of the biomaterial deliverydevice, seen from above;

FIG. 1A is an end view of the FIG. 1 body;

FIG. 2 is an elevation view of the piston;

FIG. 2A is an end view of the FIG. 2 piston;

FIG. 3 is an elevation view of the rod together with its shutter;

FIG. 3A is an end view of the FIG. 3 rod;

FIG. 4 shows the first stage of using the device which consists inputting the spheres of biomaterial into place;

FIG. 5 shows the following step which consists in putting the pistoninto place inside the body of the device;

FIG. 6 shows the following step of use in which the body is moved awayfrom the end of the rod to enable biomaterial spheres to escape; and

FIG. 7 shows the final state of the device once the piston has expelledall of the spheres into the cavity formed in the bone.

With reference initially to FIGS. 1 to 3, there follows a description ofthe various parts of the device for delivering spheres of biomaterial.

In FIGS. 1 and 1A, there can be seen the body of the device. The body 10is constituted by a tubular part 12 that thus presents an axial bore 14of inside diameter D1. This tubular part presents a first end 16 whichis provided with longitudinal slots such as 18, defining between themelastically deformable tongues 20. On their inside faces 20 a, thetongues are provided with respective catch-forming portions in relief 22for use, as explained below, as snap-fastener members. The second end 24of the body 10 is preferably provided with a flared extension 26 whichdefines a frustoconical recess 28 in the form of a funnel opening outinto the axial bore 14 of the body 10.

FIGS. 2 and 2A show the second element of the device for deliveringspheres of biomaterial, this element constituting the piston 30. It islikewise essentially constituted by a tubular part 32 that thereforepresents an axial bore 34. The diameter of the axial bore 34 isreferenced D4 while the outside diameter of the piston 30 is equal toD3. The diameter D3 is slightly smaller than the diameter D1 so as toallow the piston to slide in the body while still being “proof” againstspheres of biomaterial. At its first end 36, the piston 30 is preferablyprovided on its outside face with fluting such as 38 extending over afraction of its length. At its other end 40, the piston 30 is providedwith a drive piece 42. The length L3 of the piston 30 is longer than thelength L1 of the body 10.

FIGS. 3 and 3A show the rod of the device of the invention. This rodpresents a main portion of outside diameter D2 and it is of length L2perceptibly longer than the lengths L1 and L3 of the body and of thepiston. The rod 50 preferably presents an axial bore 52 which extendsover at least a fraction of its length and preferably over its entirelength. Close to its end 54, the rod has an annularly-shaped portion 56presenting a diameter D′2 that is perceptibly greater than the diameterD2 of the rod 50. The annular portion 56 preferably presents an annulargroove 58 whose function is explained below. The terminal portion 60 ofthe rod 50 also presents an enlarged diameter but smaller than thediameter D′2 of the enlarged portion 56. The diameter D2 is slightlysmaller than the diameter D4 of the axial bore in the piston so as to be“proof” against the spheres of biomaterial.

These various elements constituting the biomaterial delivery device arepreferably made of a steel presenting the qualities required forsurgical instruments.

With reference now to FIGS. 4 to 7, there follows a description of howthe device is used to deliver small spheres of biomaterial into thecavity formed in the portion of bone concerned.

FIG. 4 shows the rod 50 in place inside the body 10 of the device. Inthis position, the shutter-forming enlarged portion 56 of the rod 50 issnap-fastened to the body 10 of the device by means of thesnap-fastening catches 22 co-operating with the groove 58 in theenlarged portion 56. This assembly thus defines an annular volume 70between the wall of the body 10 and the outside portion of the rod 50,this volume being closed at its bottom end by the shutter 56 of the rod50. The funnel 28 is used to introduce the required quantity of smallspheres of biomaterial 72 into the annular space 70. Thereafter, asshown in FIG. 5, the piston 30 is put into place, the piston having itsaxial bore 34 engaged on the rod 50. The piston 30 is introduced intothe axial bore of the body 10 in such a manner as to cause the spheresof biomaterial 72 to be lightly compressed.

In the following step, shown in part in FIG. 6, the assembled device inthe state shown in FIG. 5 is inserted into the cavity made in the bone.The end 60 of the rod constitutes a limit on how far the device can bepushed into the cavity, thereby ensuring that it is properly positioned.In the following step, the body 10 is moved away from the shutter 56 ofthe rod 50, the rod remaining stationary. This causes the rod to bereleased relative to the body 10, thereby obtaining an opening 74between the shutter 56 and the bottom edge 12 a of the body 10. Thisopening 74 enables the spheres of biomaterial 72 to escape from thevolume in which they were initially confined. By keeping the body 10 inposition and by causing the piston 30 to be pushed in relative thereto,the transfer of the spheres 72 into the inside of the cavity isfacilitated. Pushing in the piston also serves to press the spheres 72against the inside wall. It should be added that by causing the piston30 to turn about its axis, the fluting 38 formed in its outside faceserves to improve the delivery and the distribution of the spheres 72against the wall of the cavity.

It should also be stated that the axial bore 52 provided in the rod 50serves to guide the device along the guide pin previously put into placein the cavity.

In a preferred embodiment of the device, the inside diameter D1 of thebody is about 13 millimeters (mm). Its length L1 is about 145 mm.

The outside diameter D3 of the piston 30 is about 12.4 mm so as to beless than the inside diameter D1 of the body 10, the axial bore of thepiston presenting a diameter of about 5 mm so as to be slightly greaterthan the outside diameter D2 of the rod 50 which is about 4.4 mm.

Naturally the various diameters D1, D2, D3, and D4 are imposed by theoutside diameter of the body 10 of the device, the outside diameter ofthe body itself being determined by the diameter of the cavity made inthe bone, which cavity usually has a diameter of 14 mm.

1. A device for delivering small spheres of a biomaterial into adetermined portion of a bone, said device comprising: a cylindricalhollow body for containing the spheres to be delivered, and having aproximal end for filling the spheres into the body, and an open distalend provided internally with snap-fastening means through which thespheres are delivered, the cylindrical hollow body having an innerdiameter D1 which is substantially constant from the distal end towardsthe proximal end, and which forms a closed wall between the distal endand the proximal end; a shutter-forming guide rod having a proximal end,a distal end, and a main portion that is cylindrical with an outerdiameter D2 and presenting, close to the distal end thereof, an enlargedcylindrical portion integral with the main portion and having a diametersubstantially equal to the inner diameter D1 of the cylindrical hollowbody, the enlarged cylindrical portion being constructed and arrangedfor releasable engagement with said snap-fastening means of the hollowbody to secure said rod in said hollow body, said shutter-forming guiderod being movable between a first position in which the enlargedcylindrical portion is engaged with said snap fastening means, closingthereby the distal end of the hollow body and forming within the hollowbody a space for containing the small spheres of biomaterial to bedelivered, and a second position in which the enlarged cylindricalportion extends beyond the open distal end of the cylindrical hollowbody to open the distal end of the cylindrical hollow body to permitdelivery of the spheres; and a piston comprising a proximal end, adistal end, and a cylindrical portion presenting an outer diameter D3and an axial bore of substantially constant diameter D4, the outerdiameter D3 being slightly less than the inner diameter D1 of the body,and the diameter D4 being slightly greater than the outer diameter D2 ofthe guide rod, enabling the piston to slide in an annular space definedbetween the guide rod and the body, wherein upon release of theengagement of the enlarged cylindrical portion with the snap-fasteningmeans of the hollow body, said rod is slidable within the axial bore ofsaid piston, the guide rod being greater in length than the hollow bodyor the piston.
 2. A device according to claim 1, wherein said rodincludes an axial bore opening out into the distal end that is providedwith said enlarged portion, the bore of said rod extending over at leasta fraction of the length of the rod.
 3. A device according to claim 1,wherein said proximal end of said hollow body is extended by a piecehaving a frustoconically-shaped recess opening into the inner diameterD1.
 4. A device according to claim 1, wherein said snap-fastening meansdisposed in the distal end of said body comprises longitudinal slotsformed in the distal end of said body and relief portions disposed atthe distal end of said body projecting into the inner diameter D1, saidenlarged cylindrical portion of the rod including a substantiallycylindrical side face in which a groove is formed for receiving therelief portions.
 5. A device according to claim 1, wherein said pistonis provided externally with fluting close to the distal end thereof.